SF: avoid a composition cycle when the FrameRate votes updates

SF would still do a composition if the display mode changes, but
it is not required for every frame rate vote change.

Bug: 339759346
Test: android.platform.test.scenario.gmail.OpenCloseComposeEmailMicrobenchmark#testOpenCloseComposeEmail
Change-Id: Ia01a13b1a167b3a0a67cf7be3db5e64b9405580a
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index edcc8d3..a198768 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -736,7 +736,7 @@
     status_t setActiveModeFromBackdoor(const sp<display::DisplayToken>&, DisplayModeId, Fps minFps,
                                        Fps maxFps);
 
-    void initiateDisplayModeChanges() REQUIRES(mStateLock, kMainThreadContext);
+    bool initiateDisplayModeChanges() REQUIRES(mStateLock, kMainThreadContext);
     void finalizeDisplayModeChange(DisplayDevice&) REQUIRES(mStateLock, kMainThreadContext);
 
     // TODO(b/241285191): Replace DisplayDevice with DisplayModeRequest, and move to Scheduler.